Scientific interests

I have been interested in the understanding and interpretation of a variety of different nuclear phenomena, having intimate contact with experimental developments in the field. Naming a few in detail; (a) I made contributions to the development of the modern version
of particle-vibration coupling as a central concept for the interweaving of single-particle and collective degrees of freedom. My contribution was extended to the effective interactions between single-particle and collective modes, the decay patterns of vibrational multiplets, the one-particle transfer excitation of such multiplets, polarization effects, and transition densities for exciting collective modes. Among others, the analysis of the decay of octupole-septuplet members in 209Bi is one of the most beautiful examples in which E1 polarization charge was quantitatively pinned down. (b) In the properties of deformed nuclei, especially those associated with rotational motion, I may mention my critical analysis and understanding of the physics in the band-crossing phenomena related to the cranking model, in addition to the relation of electromagnetic transitions in rotating nuclei to the nuclear shape. (c) In the search for triaxial nuclear shape I made basic predictions as to the features of electromagnetic transitions characterizing triaxial shape. I suggested and pinned down that the experimental finding by G.B.Hagemann et al. in 2001 is the discovery of wobbling mode. Then, my prediction of the presence and properties of the band with two wobbling phonons in 163Lu urged the experimentalists to look for it. The band was subsequently found. (d) Together with G.Bertsch in 1982 I pointed out that the tensor force could shift an appreciable amount of Gamow-Teller strength to the energy much higher than that of the Giant Resonance (GR), and thereby explained the considerable amount of missing strength in observed GT GR. The higher-lying GT strength was
indeed observed at the end of the nineties. (e) Together with Mottelson, Xie and Zhang in 1991 I studied the shell structure and octupole instability in Fermion systems. The study was originally intended for atomic cluster systems, but the beautiful result based on the group theory together with numerical calculations throughly worked out invited later some nuclear theorists to apply the idea also to nuclei, especially searching for the Y32 (tetrahedron) deformation. (f)In the physics of drip line nuclei I have studied (1993-present) the change of shell-structure, polarization effects, giant resonances, one-particle resonant levels etc. The study will contribute to the field exploited by radioactive-ion-beams, the facilities of which are either under operation or currently being constructed.